This paper presents a speech enhancement algorithm using a one-microphone for automatic speech recognition system. Speech signal received in an enclosed room is distorted by reflections from walls and other objectives. This distortion effect named as “reverberation” degrades the fidelity and intelligibility of input speech in acoustic systems such as hand-free conference telephones and automatic speech recognition. In this project, we consider the importance effect of reverberation on... Topics: Voice Activity Detector, reverberation, DPCM encoding, Spectral Subtraction.